Hello,
I maintain a 2.4 USB driver based off an old version of usb-skeleton.c.
(It's for an in-house tester used where I work, and the choice of kernel
version is out of my hands.) I've just taken a look at the latest (2.6)
version of usb-skeleton.c, and I'm wondering if someone would be
generous enough to explain to me how a part of it works.
It's the writes I'm wondering about. It appears that the code allocates
a new URB and buffer for each write. Once the write is completed, the
associated URB and buffer are freed. But one of the ways I benchmark
our download speeds is by filling a 4K buffer with valid packets and
looping over a single write(2) call. With the CPU being so much faster
than USB and an URB/buffer pair being allocated for each write, it would
seem like it wouldn't be long before an -ENOMEM was returned.
Of course, one answer would be, "Don't do that!" But with a sizable
number of testers connected to the same host, I could see the result
being the same, or similar, even during normal usage.
What am I missing?
Thanks,
Sam
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